Carburetor



Jan. 30, 1934. F c. MQK 1,945,200

CARBURETOR Filed Sept. 4, 1930 2 ii ai 23 z 22 25 19 "13 X H H! 1% X I'1 -7; X 5.

fifi/V/r- 05K 27 f 14 BY Patented Jan. 30, 1934 UNITED STATES PATENTOFFIC CARBURETOR Application September 4, 1930. Serial No. 479,627

3 Claims.

It is well known in the carburetor art that athermal control of theaccelerating discharge is desirable. With an intake system too cool forinstantaneous vaporization of the fuel, very much better operation andresponse to the throttle is obained with an accelerating charge ofvolume equal to several cylinder charges, delivered when the throttle isopen. With a properly designed carburetor, when the intake system is sowarm that it contains no liquid gasoline, no accelerating 1 charge isnecessary and even a very little is highly detrimental. There have beenproposed for acceleration various piston and diaphragm pumps embodyingin their construction a dome which contains air when gasoline is firstadmitted to the carburetor, and a little air and considerable gasolinevapor, after the carburetor has been heated and cooled a numberof-times. In this latter condition, the

contents of thedome chamber of the pump would be liquid gasoline whenthe engine is cold and vapor when the engine is warm. In'every case,however, the resistance to delivery from the pump is so slight thatsubstantially the full volume of displacement is delivered as, adischarge.

An object of this invention is to provide a carburetor in which theaccelerating charge is controlled according to the operating temperatureof the intake system.

Another object of this invntion is to provide a carburetor in which theaccelerating pump de-' livers a full accelerating charge equal in volumeto several cylinder charges when the intake system is cool andsubstantially no accelerating charge when the intake system is warm.

Another object of my invention is to provide a carburetor in which theaccelerating discharge is controlled according to the volatilityof thefuel. Still another object of my invention is to devise an accelerationpump in which the dome chamber is relatively large in proportion to thepump displacement, and the outlet valve is controlled by aspring ofconsiderable resistance, say equivalent to seven pounds per square inch,so that when the dome chamber is filled with vapor, the

I outlet valve will not be open. With such an ar-.

rangement, the displacement of the' pump will be largely or wholly takenup in compressing the vapor and little or no fuel will be delivered bythe action of the pump. If the carburetor werecooled slightly so thatthe dome chamber were filled with vapor only equal to the displacementof the pump, the first half of the pump stroke would be required toraise the dome pressure to a point where it would open the controlvalve, and the second half of the pump stroke would deliver fuel, and soon. Because of this delay'in action, it is preferable to have the pumpoperated by manifold vacuum.

With these and other objects in view which may be incident to myimprovements, my invention consists in the combination and arrangementof f elements hereinafter described and illustrated in the accompanyingdrawing in which: Figure l is a vertical section of acarburetorembodying my improved accelerating device, 7 Figures 2, 3 and 4 arefragmentary sectional views somewhat diagrammatic, illustrating. thegeneral principle of vapor control of the pump action,

Figure 5 is a modified form of accelerating device which is controlledby manifold vacuum and'in which a diaphragm is substituted for thepiston in Figure 1.

Referring first to Figures 2, 3 and 4, the reference numeral 1 denotes afuel chamber which y communicates through a small orifice 2 with a pumpcylinder 3 in which reciprocates an air tight piston ,4. Near thebottomof cylinder3 is a relatively large escape port 5 controlled by a springpressed check valve 6. Figure 2 depicts what happens when fuel is firstadmitted to cylinder 3 from chamber 1, i. e. air is trapped under piston4. If now the temperature of the device rises, the air expands andescapes as bubbles through the communicating port 2; also vapor risesfrom the liquid in cylinder 3 and begins to occupy the space under thepiston. This causes a partial displacement of the air with the resultthat bubbles of both air and vapor escape through port 2. If-thisprocess were continued long 95 enough, practically all the air would beexpelled and only vapor left in cylinder 3,. as indicated in Figure 3. l

Figure 4 shows what happens if the device is then cooled to its originaltemperature; the vapor condenses and liquid fuel is drawn up to fill thespace under the piston. If the device is then again warmed up to thetemperatureof Figure 3, vapor will be generated and fill the space incylinder 3 above port 2. To obtain the regulation desired, the spring ofthe outlet valve 6 is made of such a tension that it will not open underthe compression generated in'the pump cylinder 3 .when the dome of pumpcylinder is filled with air or vapor. Obviously, it

will have to open when the pump is operated if the dome is full ofliquid.

In the embodiment shown in Figure 1, the reference numeral 10 denotes afloat chamber filled with fuel to a constant level X-X. The fuel passesdownward from chamber 10 through a flat disk check valve 11 to main jet12 of the carburetor, and is drawnfrom this jet by the suction of theair through the Venturi tube 13 in the usual manner. Connected withfloat chamber 10 by a small orifice 14 is a pump cylinder 15 with anadditional dome 16 which in turn is connected to the fuel passage by aspring pressed check valve 17. Reciprocating in cylinder 15 is anair-tight hollow piston 18 which is connected through link 19 and lever20 to a cam 21 on shaft 22 of throttle 23. A spring 24 surrounding link19 bears against the end of lever 20 and keeps it in contact with cam21.

When fuel is first admitted to the carburetor, dome 16 and also thespace in piston 18 will remain full of air, but after the carburetor hasonce been heated up to the boiling point of the most volatile fractionof the fuel, these spaces will largely lose their aircontents and befilled tirely filled with liquid fuel. The force of the spring of valve17 is so proportioned to the volumes 16 and 18- and the displacement ofpiston 18 upon its downward stroke, that when the carburetor is hot,operation of the pump will not produce enough pressure in 16 and 18 asto move valve 17 off its seat; with the carburetor cold, and no air inthe pump, almost the whole displacement of piston 18 will be dischargedthrough valve 1'7, (except for leakage through port 14 and past thepiston 18). It will be observed that when discharge occurs through valve17, check valve 11 is raised against its seat, thus preventing flow fromthe accelerating pump into the float chamber. During the short time' thepiston 18 is descending when the pump is operated quickly, the back flowof fuel through port 14 is negligible due to the restricted size of theport. Also, due to the continuous opening of port 14, the discharge ofthe pump is necessarily less when the pump is operated slowly than whenit is operated quickly, as is desirable, because slow opening of thethrottle does not require as much accelerating discharge .asa quick one.

It will be noted that the theoretical device shown in Figures 2, 3 and'4does not have a gradual operation with a change in temperature, butchanges rather abruptly as the tem-- perature of the fuel passes theboiling point of its lightest fractions. To obtain a certain graduation,two chambers, '16 and 18, are provided. As heat is usually received bythe carburetor both from the air going through it and by conduction fromthe engine to which the carburetor is bolted, chamber 16, which is anintegral part of the carburetor casting, will usually be warmer than thespace in piston 18, which is separate from the body of the carburetor.The dome 16 will therefore empty sooner than space 18, and a graduatedcontrol is thereby obtained. A screw threaded needle valve 25, isprovided as a means of venting the dome 16 when the engine is cold,therebv bringing the pump into full action at once wait ing for aninitial heating up.

Figure 5 shows an arrangement in which a vacuum actuated diaphragm 26 issubstituted for the mechanically operated piston 8 of Figure 1.Diaphragm 26 is secured in a, supplementary chamber 27 below the floatchamber 10 in such a position that its upper surface is subject tofluctuations in vacuum above throttle 23 through passageway 28. Thespace in chamber 27 corresponds to that in piston 18 in Figure 1, and isfilled with fuel through restricted port 14. The construction shown inFigure 5 also differs from the construction of Figure 1 in that the pumpis refilled from the passage between the metering orifice and the jetoutlet; the orifice, 14, in this case is made very small, so thatclosing of the throttle 23 gives a very slow refill, which is sufficientto make the main jet 12 discharge about 10% leaner during the timerefill takes place.

From the foregoing description, it is clear that I have devised a noveland effective means for automatically controlling the acceleratingdischarge according to temperature and to volatility of the fuel. 1

,While I have shown and described the preferred form of my invention, Idesire it to be understood that I do not intend to be confined to theconstructional details shown as these may be modified and changed bythose skilled in the 3 art without departing from the spirit of myinvention or exceeding the scope of the appended claims.

I claim:

1. In a carburetor, an accelerating pump com- 1 prising a cylinder, apiston in said cylinder, an auxiliary dome chamber communicating withsaid cylinder, and a pressure actuated outlet valve controlling the flowof fluid from said cylinder and chamber, said chamber being of such size1 relative to the displacement of said piston that said outlet valvewill not open when said chamber is filled with vapor but will open whensaid chamber is partially filled with liquid fuel.

2. In a. carburetor, an accelerating pump com- 1 prising a cylinder andpiston therein; an auxiliary' dome chamber communicating 'with saidcylinder, a pressure actuated outlet valve regulating the flow of fluidfrom said cylinder and chamber, said valve being controlled by a spring1 and said chamber being of such size relative to the displacement ofsaid piston that when said chamber is filled with vapor, the internalpressure developed by the displacement of said piston is insufiicient toovercome the force of said spring 1 and open said valve.

3. In a carburetor, an accelerating pump comprising a cylinder, aninverted cup shaped piston in said cylinder having an imperforate upperportion for containing vapor, an auxiliary vapor 1 chamber communicatingwith said cylinder, and a pressure actuated outlet valve controlling theflow of fluid from said cylinder and chamber, said chamber being of suchsize relative to the displacement of the piston that the outlet valvewill not open when the chamber is filled with vapor but will open whenthe chamber is partially filled with liquid fuel.

FRANK C. MOCK. 1

